People have a right to defend themselves. If you own a gun and are smart you will make sure you learn how to use it properly. Criminals usually don't. I can't speak to this specific case but guns are very often used to deter or stop criminals (https://fee.org/articles/guns-prevent-thousands-of-crimes-every-day-research-show/)

You will see other statistics that say that the risks of owning a gun outweigh the benefits. However, I think that is largely dependent on how responsible you are as a gun owner.